Light diffusors for illuminating devices



Nov. 15, 1960 E. F. GUTH, sR 2,960,604

LIGHT DIFFUSORS FOR ILLUMINATING DEVICES Filed April l2, 1957 un I....L-Am-EMI.

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LIGHT DIFFUSORS FOR ILLUMINATING DEVICES Edwin F. Guth, Sr., St. LouisCounty, Mo., assignor to The Edwin F. Guth Company, St. Louis, Mo., acorporation of Missouri Filed Apr. 12, 1957, ser. No. 652,499

9 Claims. (ci. 24o-7s) This invention relates generally to the controlof light, and particularly to grids or lattices for use in connectionwith lighting fixtures and in other situations where it is desired tocontrol light between the source thereof and the region upon which theillumination is desired.

In applicants Patent No. 2,745,001, granted May 8, 1956, the latticedefines between the walls thereof a multiplicity of generallyrectangular open spaces adapted to control the light from a suitablelight source and passing through the lattice. Such lattice in theembodiments described is of a molded material.

In the construction of the patent, the cut-off angle of the lightpassing through any open space without diffusion is determined by thewalls surrounding the open space and defining a planar aperture at thetop and bottom thereof, so that the light passing directly through theaperture is restricted by the angle determined by the edges of oppostewalls at the top and bottom.

One of the objects of this invention is to provide a lattice soconstructed as to increase the light passing through the aperture beyondthe normal cut-ofi angle of the wall at the entrance to the bottom ofthe opposite Wall at the exit without introducing objectionable glare,or otherwise mlitating against the comfortable seeing conditionsproduced by the louver of the aforesaid patent.

Further objects will appear from the detail description in which will bedescribed a number of embodiments of this invention; it is to beunderstood, however, that this invention is susceptible of variousembodiments within the scope of the appended claims.

Generally stated, and in accordance with illustrative embodiments ofthis invention, the light controller com prises a lattice oflight-transmitting material defining between the walls thereof amultiplicity of non-planar apertures which are formed to increase thecut-ofi angle for a limited amount of the light passing through theaperture. The structure is such as to variably increase such cut-offangle along the walls of individual apertures. While the cut-ofi may bein only one direction or in two opposite directions with respect to thearea of the lattice, the cut-off may be in transverse directions withrespect to the area of the lattice. In the illustrative embodiments, theabove result is accomplished by varying the depth of at least some ofthe walls which bound an aperture and, particularly by reducing thedepth transversely along the walls. In order to secure optimum results,the wall depths are reduced at spaced intervals around each aperture.

In the accompanying drawings:

Figure 1 is a perspective view of a luminaire provided with a lightcontroller constructed in accordance with this invention;

Figure 2 is a face view of one embodiment of the light controller;

Figure 3 is a section on the line 3 3 of Figure 2;

Figure 4 is a section on the line 4 4 of Figure 2;

Figure 5 is an enlarged diagrammatical detail show- 2,960,604 PatentedNov. 15, 1960 'ice ing the optical principles involved in theconstruction of Figures 2-4;

Figure 6 is a view similar to Figure 2, but showing another embodimentof this invention;

Figure 7 is a section on the line 7 7 of Figure 6;

Figure 8 is a section along the line 8 8 of Figure 6;

Figure 9 is an enlarged diagrammatical detail showing the principlesinvolved in the embodiment, Figures 6-8;

Figure 10 is a view like Figure 3, but illustrating another embodimentof this invention;

Figure 11 is a view like Figure 3, but illustrating another embodimentof this invention; and

Figure 12 is a view like Figure 10, but showing another embodiment ofthis invention.

Referring to the accompanying drawings, and more particularly to Figure1, 1 designates the fixture which may be supported in any suitablemanner as in the ceiling 2 of a room. A frame 3 supports the lightcontrolling lattice indicated generally at 4 in any suitable manner, asin Patent No. 2,745,001. The fixture is provided with one or more lamps5 which may be of a fiuorescent type or of an elongated filament typesupported in receptacles 6. These lamps are, therefore, in a position todirect light on the top or entrance of the diffusing lattice to issue atthe exits thereof. The fixture itself may be provided with reflectors(not shown) on the inside thereof to further direct the light on thelattice.

Referring first to Figures 2-4, and also to Figure 5, the lattice has aseries of walls 7 and 8 which define therebetween a multiplicity of openspaces 9 and whose edges define apertures 10 and 11, at the oppositefaces of the lattice. The open spaces 9 are generally cubic, but atleast one of the apertures, such as 10, being non-planar. To accomplishthis, the edges of the walls 7 are recessed as shown at 12 at one faceof the lattice to form spreading V-shaped valleys thereby reducing theheight of the walls progressively from the corners of an aperture to amidpoint of its side. In other words, the edges are configurated so thatpoints therealong lie at varying distances from the center plane of thelattice, the configuration being repeated at each opening. As shown, theWalls 7 are provided with a valley at opposite sides of each aperture.

Figure 5 illustrates the optical principles of the lattice of Figures2-4. As an example, the walls 7 and 8 are 1/16 inch thick and V16 inchin height (vertical). The distance between the walls is 6/16 inch. Thedepth of each valley 12 is 2/16 inch. The cut-off angle for a beam oflight a, a', passing adjacent the corner of aperture 10, is 45 to thehorizontal. The cut-ofi angle is, however, gradually decreased from thecorners of aperture 10 so that, at the apex of valley 12, it is about 35to the horizontal. Thus, through each of the valleys 12 there emerges atriangular pyramid of direct light in addition to that which wouldemerge through a planar aperture. The magnitude of this additionaldirect light, relative to the whole of the light transmitted, isinsufficient to produce objectionable glare, but at the same timesubstantially improves the efficiency of the louver.

ln the embodiment shown in Figures 2-4, the cut-ofi angle will bedecreased beyond the normalcutoff angle in one dimension o-f thelattice, viz., in the dimension parallel with the line 3 3 in Figure 2.

In the form shown in Figures 6-9, both cross walls are recessed at edgesdefining one face of the lattice to increase the cut-off angle intransverse directions, with respect to the area of the lattice. This isaccomplished by forming the walls 8 with valleys 13 in addition to thevalleys 12 in walls 7. Figure 9 shows the optical principle of thisconstruction which is similar to that in Figure 5, so that the samereference numerals are applied. In this embodiment, therefore, bothwalls are reduced in depth at spaced intervals around each aperture.This construction is of advantage where the lattice forms a large partof the ceiling of a room so as to be directly over, back and front, andleft and right, of the person or object illuminated.

Figure l shows an embodiment in which the walls -8 are reduced by curvedindentation 14 instead of by two lines forming a V-shaped valley.Theoperation is, however, substantially that of the construction shownin Figures 5 and 9. In Figure 11, the construction is the same as thatshown in Figures 2-5 except that walls 7 of the lattice are increased invertical depth by V-shaped projections 15. This neutralizes the Aeffectof valley 12 as to light Vrays from point sources directly in line vwithvertices of projection 15 and valley 12, and further modifies vthecharacter of the light passing through the louver. Obviously, theprojections 1'5 may be Yprovided on one or both of walls 7 and il.

In Figure 12, the construction is like that of Figure l0 except thatwall '8 is increased in depth by providing arcuate projections 16. `Itwill be understood that the projections 16 may be provided on both ofwalls 7 and 8.

The light controller may be constructed in any suitable manner, but asva practical embodiment, it is molded of a plastic light-transmittingmaterial. The material may be glass or one of the transparent resins,such as methylmethacrylate or polystyrene, clear or frosted. Suchsynthetic resins lend themselves readily to molding under pressure in asectional mold in which the mold surfaces can be highly polished.Likewise, although glass is more d-itiicult to press in large areas thansynthetic resins, the lattice can be made of an area which lends itselfto pressing and the glass may then be annealed in any suitable manner.The pressing may be done in sectional molds of a character used in themaking of .artificial cut glass trays and bowls. Likewise, a syntheticresin, such as Lucite, may be pressed in sectional molds of thecharacter employed yin making taillight reliectors for automobiles.Sections ofV the ylattice may be placed end .to end and side to side toform an area of any desired extent. In such a case, the projecting endsZtl-.of two lattices will form complete apertures.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

.1. A light controller,comprising, a lattice of lighttransmittingmaterial formed .by a series ofparallel walls intersecting anotherseries of parallel walls perpendicular to the first series, the edgesofsaid walls collectively defining opposite faces of the lattice, thewalls defining a multiplicity of open spaces therebetween and the edgesof the walls defining apertures at the opposite faces of the lattice,the aperture-dening edges of parallel Awalls being of a serpentineconfiguration repeated from Yaperture to aperture so that pointstherealong areat varying distances from a virtual surface midway betweenvsaid opposite faces ofthe lattice, thereby to produce a varying lightcut-off effect across each `opening ofthe lattice.

2, A light controller as set forth in claim 1, wherein the points alongsaid serpentine edges closest to said virtual surface are locatedcentrally between the walls which intersect said serpentine-edged Walls.

3. A light controller as set'forth Vin claim 1, wherein the points alongsaid serpentine edges most remote from said virtual surface are locatedcentrally between the walls which intersect saidA serpentine-edgedwalls.

4. A light controller as set forth in claim l, wherein all parallelwalls have the same edge configuration.

5. A light controller as set forth in claim 1, wherein all walls havethe same edge configuration, all walls being spaced from one another auniform distance.

6. A light controller, comprising a lattice of lighttransmittingmaterial formed by a series of parallel Walls intersecting anotherseries of parallel walls perpendicular to the first series, the edges ofsaid walls collectively defining opposite faces of the lattice, thewalls defining a multiplicity of open spaces therebetween and the edgesthereof defining apertures at the opposite faces of the lattice, theaperture-defining edges on one face of the lattice having a repeatedindented edge configuration such that the points thereof at saidintersection lie at a maximum distance from a virtual surface midwaybetween said opposite faces of the lattice, whereas the points of saidedges centrally between said edges lie at a minimum distance from thecenter plane o-f the lattice.

7. A light controller as set forth in claim 6, wherein theaperture-defining edges at the other face of the lattice all lie in acommon plane.

8. A light controller, comprising, a lattice of lighttransmittingmaterial formed by a plurality of intersecting vwalls whose edges definethe opposite faces of the lattice, the walls defining a multiplicity ofopen spaces therebetween and the edges of the walls defining aperturesat the opposite faces of the lattice, the aperturedefining edges ofparallel walls being of a serpentine configuration repeated -fromaperture to aperture the serpentine configuration being in a directionsuch that points therealong are at varying distances from the centerplane of the lattice and the points along said serpentine edges closestto the center plane of the lattice are located centrally between thewalls which intersect said serpentineedged walls, thereby to produce avarying light cut-off effect across each aperture of the lattice.

9. A light controller, comprising, a lattice of lighttransmittingmaterial formed by a plurality of intersecting walls Whose edges definethe opposite faces of the lattice, the walls defining a multiplicity ofopen spaces therebetween and the edges of the walls defining aperturesat the opposite faces of the lattice, the aperturedefining edges ofparallel walls being of a serpentine configuration repeated fromaperture to aperture the serpentine configuration being in a directionsuch that points therealong are at varying distances from the centerplane of the lattice, and the points along said serpentine edges mostremote from the center plane of the lattice are located centrallybetween the walls which intersect said serpentine-edged walls, therebyto produce varying light cut-off effects across each aperture of thelattice.

References Citedin the file of this patent UNITED STATES PATENTS2,506,951 Doane May 9, 1950 2,597,739 Lacy et al. a May 20, 19522,606,998 Winkler et al. Aug. 12, 1952 2,710,335 i/Vong .lune 7, 19552,745,001 Guth May 8, 1956 2,756,325 Zwick -V July 24, 1956 2,837,632Lipscomb lune 3, 1958 FOREIGN PATENTS 593,235 Great Britain Oct. 10,1947

